Yes, i noticed this too, but not always...
I'm quite sure it's PC and/or graphic card performance related imo.
Running I7 875K, Zotac 580 1.5Gb, 16 Gb RAM, and Dynamic Environment waves (realistic) strange thing is 80% of time, waves are mouving very fluent and other 20% of time waves kind of slow down in their animation (when they are quite big - up to 8/10 knots wind i can't see any slow down).
If i could see my PC usage ingame, i'm sure the little slow down is due because something else is sucking power somwhere else
Having big modding list is not helping either!
No big deal for me cause it's not that often.